1. Field of the Invention
The present invention relates generally to video processors for processing video input signals to provide a video output signal for application to a video tape recorder or the like, and, more particularly, wherein the video output signal has modified vertical sync pulses to discourage or prevent duplication of the video output signal after the initial recording thereof.
2. Prior Art Statment
Since the advent of cable TV, various methods and devices have been proposed to modify the NTSC standard composite video signal so as to prevent satisfactory reception and display at a non-authorized receiver unit. Exemplary embodiments of such devices may be found in U.S. Pat. No. 3,460,161, issued to Waller et al., and U.S. Pat. No. 3,530,232, issued to Reiter et al. However, such techniques have proved inappropriate to prevent the duplication of video tape recordings which are now being marketed to supply the rapidly increasing numbers of "home" video tape recorders. Consequently, such methods as those taught in U.S. Pat. No. 3,963,865, issued to Songer, and U.S. Pat. No. 4,030,128, issued to Perret, have been proposed to solve this problem.
To facilitate examination, copies of each of the above patents are submitted herewith.